Zeeshan Akhter

Disciplines

Material Chemistry, Physical Chemistry, Photonics

Laboratory

LABORATORY OF PHYSICAL CHEMISTRY

Host institution

UNIVERSITE PARIS 11

Other institution

Université Paris-Saclay

Doctoral school

SCIENCES CHIMIQUES : MOLECULES, MATERIAUX, INSTRUMENTATION ET BIOSYSTEMES – ED 571

Description

The titanium dioxide TiO₂ exhibits photocatalytic activity that was first considered harmful, because it leads to the degradation of organic matrices in which the white pigment is incorporated. The ability to use these properties in applications related to the environment and energy, such as the elimination of organic pollutants in water and air or hydrogen production, has generated renewed interest in the scientific community for TiO₂.

 

The objective of this work is the development of a mesoporous TiO₂-based photonic crystal (Bragg stacks) showing a high photocatalytic activity, photon tenability and activity in the visible range. The development of a material with specific properties requires an understanding of the relationship between the elaboration, structure (crystalline structure and microstructure), the dynamics of charge carriers (electronic properties) and the photocatalytic activity of the material. This requires two steps coupled between them: Elaboration versus Characterization (structural, electronic and photocatalytic).

 

In this work, the mesoporous photonic crystal will be obtained by alternating thin mesoporous films of TiO₂ and other semi-conductors using soft-chemistry (sol-gel process). The mesoporous TiO₂ films will also be coupled by plasmonic nanoparticles (localized into the pore) by gamma radiolysis of metal complexes. The synthetic procedure will be tuned to insure an optimal film’s interconnection, thickness, crystallinity, optical properties, electron transfer, light harvesting etc.

 

The electronic properties will be studied by Time Resolved Microwave Conductivity (TRMC) to measure the lifetime of charge carriers created by illumination of the photocatalyst. The structure, texture and optical properties of the mesoporous photonic structure will be assed will be characterized using Time Resolved Microwave Conductivity (TRMC), UV-visible spectroscopy, FTIR spectroscopy, X-ray diffraction and scanning electron microscopy.

 

The photocatalytic properties of the samples will be determined by photodegradation of phenol in water and hydrogen production from methanol.

Skills required

chemistry

Bibliography

– Graphene oxide-TiO2 and reduced graphene oxide-TiO2 nanocomposites: Insight in charge-carrier lifetime measurements. Kusiak-Nejman, E.; Wanag, A.; Kowalczyk, Ł.; Kapica-Kozar, J.; Colbeau-Justin, C.; Mendez Medrano, M. G.; Morawski, A. W. Catal. Today 1:1−15 (2017) – Ta-doped TiO2 as photocatalyst for UV-A activated elimination of chemical warfare agent simulant. Keller, V.; Sengele, A.; Robert, D.; Keller, N.; Herissan, A.; Colbeau-Justin, C. J. Catal. 334:129−141 (2016) – Synergetic Effect of Ni and Au Nanoparticles Synthesized on Titania Particles for Efficient Photocatalytic Hydrogen Production. Luna, A. L.; Novoseltceva, E.; Louarn, E.; Beaunier, P.; Kowalska, E.; Ohtani, B.; Valenzuela, M. A.; Remita, H.; Colbeau-Justin, C. Appl. Catal., B 191:18−28 (2016) – Ordered and disordered evolution of the pore mesostructure in hybrid silica anti-reflective films obtained by one-pot self-assembly method. Ghazzal, M.N., Debecker, D.P., Gaigneaux, E.M. Thin Solid Films 611:117−124 (2016) – Tailored refractive index of inorganic mesoporous mixed-oxide Bragg stacks with bio-inspired hygrochromic optical properties. Ghazzal, M.N., Deparis, O., De Coninck, J., Gaigneaux, E.M. Journal of Materials Chemistry C 1:6202−6209 (2013) – Porosity control and surface sensitivity of titania/silica mesoporous multilayer coatings: Applications to optical Bragg resonance tuning and molecular sensing. Ghazzal, M.N., Deparis, O., Errachid, A., Kebaili, H., Simonis, P., Eloy, P., Vigneron, J.P., De Coninck, J., Gaigneaux, E.M. J. Mater. Chem. 22:25302−25310 (2012)

Keywords

mesoporous material, sol-gel chemistry, photocatalysis, Bragg stacks, hydrogen generation, thin films

 

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